A wide variety of products are conventionally packaged in bulk in relatively large bags which are formed with valve means in one of the end flaps of the bag. Such bags, referred to in the industry as "valve bags" or "valved bags," are usually formed of a heavy paper, but sometimes they are formed of plastic material or include a plastic liner. The valve in these bags is constructed so that it can be opened to permit a fill spigot to be positioned inside the valve opening, either by moving the bag over the spigot or the spigot into the bag. Once filled, the material inside the bag tends to flatten the end flap and automatically close the valve against accidental discharge of material from the bag.
Numerous apparatus have been developed for the automatic, sequential opening of valve bags and positioning or placing of the same on the fill spigot. Typical of such apparatus are the devices set forth in the following U.S. Pat. Nos.: 3,213,588, 3,423,903, 3,676,977, 3,691,715, 3,715,858, 3,884,278, 4,128,116, 4,141,392, 4,158,943 and 4,213,212. Valve placer apparatus such as the devices set forth in the preceeding patents generally include a bag magazine, a feeding assembly which removes bags from the magazine and feeds them sequentially to an assembly formed to orient the bag and the end flap containing the valve, a bag opening assembly formed to open the valve after orientation of the same, and a bag filling assembly formed to fill the bag through the fill spigot.
While prior art automatic bag placers have included all of the necessary assemblies for automatically feeding bags to a fill spigot, considerable problems have been encountered in connection with reliable operation of such apparatus. Thus, prior bag storage magazines have been constructed in a manner which causes multiple bags to be withdrawn from the magazine, instead of a single bag. Bag feeding and orienting assemblies have not reproducibly manipulated the bags and valves to enable opening of the same. Bag opening and filling assemblies have not reproducibly opened and positioned the open bag on the fill spigot. Additionally, such bag placer apparatus tend to be undesirably complex in structure and slow in operation.